Varnish film for insulating purposes



Jan. 2, 1923. 1,440,448

P. E. DEMMLER. VARNISH FILM FOR INSULATING PURPOSES.

FrLEDJAN. 16, 1919.

WITNESSES:

hantai Jan. 2, 1923.

UNITED sTATEs `vPATENT OFFICE.

yPAUL E. DEMMLER, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB -TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

VARNISH FILM FOB INSULATING PURPOSES.

Application led anuary 16, 1919. Serial No. 271,546.`

To all whom t may cofwern:

Be it known that I, PAUL citizen ofthe United States, and a resident of'Pittsbui-gh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Varnish Films for Insulating Purposes, of which the following is. a specification.

My invention relates to electrical insulating material and it has, for its primary ob- `ject, -the provision Vof a method by which relatively thin sheets of such material having a high dielectric strength .may be formed.

One object of my invention is` to provid an insulating material in 4bthe form of a relatively -thinres'ilient sheet possessing great tensile strength, as well as high dielectric strength. .l

Another object of my invention is the provision of such 'insulating ma'telrial by amethod which shall promote rapid production thereof.

A still further object lf'my invention is the provisionof' relatively thin sheets which may be made any desired thickness and of i any length convenient to handle.

A With these'and other objects in view, my invention will be more fully described, illustrated in the drawings, in the several views of which correspon ing .numerals indicate' particularly pointed out like parts, and then in the' claims. f

In the drawings, Fig. l is a sectional view parts being broken away, of a metal foil.

having a coating of insulating material; Fig. 2 is a sectional view, parts being broken away, of a lm di' insulating material, and Fig. 3 is a plan view, parts being broken away,.of the film of insulating materia -A shownin Fig. 2.

In practising my invention, I may 'provide insulating material by employing metal foil and subjecting it to treatment in a bath of insulating material sufiiciently adhesive tocoat the metal foil, after which the foil maybe drawn throughV a. drying tower to thoroughly dry the coating of insulating material. Afterl the foil has been coated and the lcoating dried, the insulating mate- -1 E. DEMMLER, a

oughly, it may be subjected to heat at substantially 2000 to 210o C..so as to keep well 'below the possible softening point of the foil. The rate of movement of the film through a drying tower, where such heat is employed, will depend upon the length of the drying tower, care being takernto insure the varnish or coating on the foil being satisfactorily dried. I

Obviously, the width and length of the foil and, consequently, the coating of varnish may beregulated as desired. After the foil has beensubjected to thebath inthe varnish and the varnish has been dried, the film of varnish covering either or both vsides of the foil may be removed therefrom to pro` vide relatively thin, tough sheets of material possessing a high dielectric strength. In some instances, the lm may be removed more readily by subjecting the foil coated Withthe varnish to a bath in molten parafine containing 10% carnauba wax, and allowing it to remain for several hours therein. This has a tendency to toughen the film. 'and to reduce its adhesion to the foil to such an extent that it maybe more readily removed therefrom.

0n account of the -characteristics possessed by a film of insulating material pro` vided asabove described, a wide variety of uses may be found'therefor. Its inherent tensile strength, coupled with its-resiliency,

allows its application in many electrical devices. For example, itmay be utilized in any device where mica or similar insulating have described, Specifically, a' l through a bath of baking varnish, drying the varnish on the foil, disposing the foil in molten Wax and removing the varnish by strippinga continuous film from each sideA of the foil. I

3. A method of making insulating material that comprises drawing a metal foil 'through a bath of baking varnish, drying the varnish on .the foil, disposing the foil in molten paraiine containing Y10% carnauba wax and removing the varnish by stripping a continuous film from each side of the foil.

LA method of making insulating material'thatcomprises forming' a film of baking varnish upon a metal foil comprising substantially 85% lead and 15% tin and removing the film therefrom.

5. Electrical insulating material comprising a self-sustaining lilm of baking varnish.

6.1Electrical insulating material comprising a resilient self-sustaining sheet of baking varnish.

In testimony whereof, I' haveA hereunto subscribed my name this 31st day of Dec. 1918. 4

PAUL E. DEMMLER. 

